A calcaneal osteotomy is a form of surgery for correction of severe hind foot misalignment. During the procedure, the heel bone (calcaneus) is cut, and the tuberosity is moved medially toward the inside or laterally toward the outside, depending upon the direction of the misalignment that is to be corrected. For example, if the patient has flat feet, the heel may be offset medially to shift the hind foot toward the inside to improve the weight distribution on the foot. On the other hand, if the patient has a high arched foot the calcaneal osteotomy may be performed to shift the hind foot laterally, to improve stability and reduce risk of sprain. This procedure has been performed by cutting the bone, moving the tuberosity medially or laterally, and driving screws through the tuberosity into the anterior calcaneus. Some of the challenges associated with this approach are determining the amount of intra-operative offset that is achievable, the capability of fluoroscopy techniques for targeting and placing of screws, and post-placement screw head prominence.
Implants are known for insertion during calcaneal osteotomy. For example, the assignee of this patent application, Wright Medical Technologies, has developed the DARCO® DPS plate, which provides support. This implant includes an anterior plate, a posterior plate, and an offset segment connecting the anterior and posterior plates. The DARCO® DPS plate is available with different amounts of offset between the anterior and posterior plates.
U.S. Patent Application Publication No. 2011/0009866 describes an osteotomy plate having a top side and a bottom side, with a first end and a second end aligned along a longitudinal axis and joined by a middle section. The first end includes a cutting edge having a chamfer of between about 5° and 30°. As a screw hole in the first end forms an angle of from about 10° to about 45° with respect to the longitudinal axis of the plate. The screw hole is not threaded, but does include an arcuate shroud on the top side of the plate. The second end has a locking hole which includes internal threads. The first hole and the second hole are aligned along the longitudinal axis. One or more of additional screw holes, compression holes, fenestrations or guide wire holes are provided.
Improved osteotomy plates are desired.